Lapping machines



Sept. 6, 1966 D couLos 3,270,465

LAPPING MACHINES Filed July 12, 1963 5 Sheets-Sheet 1 W I v F76.

IN V EN TOR.

p 6, 1966 J. J. DECOULOS 3,270,465

LAPPING MACHINES Filed July 12, 1963 3 Sheets-Sheet 2 INOR.

J. J. DECOULCIDS 3,270,465

LAPPING MACHINES Sept. 6, 1966 3 Sheets-$heet 3 Filed July 12, 1963 IN VE/VTOR United States Patent 3,270,465 LAPPING MACHINES John J. Decoulos, 18 Calumet St., Peabody, Mass. Filed July 12, 1963, Ser. No. 294,596

' 3 Claims. (Cl. 51-98) This invention relates to improvements in machines for removing material through the use of abrasive mixtures. In the slicing or wafering of hard and friable materials, such as quartz, semi-conductor materials, gem stones and Watch stone materials, it is common to use thin diamond grinding wheels. Also, expensive diamond grinding wheels are used to grind and sharpen materials such as tungsten carbide, ceramic, and super high speed steels such as grade T15. In some cases where dimensional accuracy can be sacrificed, inexpensive silicon carbide wheels may be used. However, because these wheels must be of a soft grade to continually expose sharp abrasive grains to the work, they have poor form retaining properties. In both the above applications, grinding wheel life is low due to the high hardness of the materials being ground. Also, the area of material in contact with the grinding wheel must be kept to a minimum due to the high material hardness and to keep generated heat to a minimum. Because of the high speed nature of grinding, additional heat is generated during the grinding process which increases the tendency to crack and chip brittle materials. Also, high forces are developed during grinding causing retained stresses in the material being ground. These retained stresses may seriously weaken the material and eventually cause breakage.

The present invention overcomes the above difficulties by providing a simplified machine to process hard to grind materials. A carrier wheel is provided on a horizontal axis, the lower portion of which is immersed in an abrasive suspended in oil, retained in a trough directly below the carrier wheel. As the wheel rotates, the abrasive mixture is carried upward on the surface of the wheel from the trough reservoir. Work is held against the surface of the wheel causing the abrasive grains to force their way between the wheel and the work. The rolling action of the abrasive causes it to remove material from both the work and the wheel with no restriction on the amount of work area against the carrier wheel. It will be understood that the more viscous the abrasive mixture, the more it will force the abrasive particles between the wheel and the work, and the faster the cutting action. Also, I have found that the higher the concentration of abrasives in the mixture, the fast the cutting action. There are two main problems with this approach in conventional lapping operations: flowability of the mixture and proper suspension of abrasive particles. These are automatically accounted for in my invention. The rotating wheel constantly agitates the mixture keeping the particles in uniform suspension, while the surface of the wheel carries the particles to the work area. In fact, the wheel carries the particles easier when the mixture has a high viscosity. Also, it is obvious that recovery or reuse of the abrasive occurs automatically. The abrasive drops back into the trough reservoir from the work or is carried back by the wheel, thereby obtaining more life from the abrasive.

A primary object of this invention is to provide a machine for processing hard materials which is capable of removing material economically and without undesirable heat by automatically applying a concentrated mixture of abrasive directly to the work area, in contrast to the random application of abrasive in conventional lapping operations. Another object of this invention is to provide a machine adaptable to many applications by utilizing different wheels and tool holders in the same machine base.

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The manner in which these and other objects of this invention are attained will become apparent from the detailed description of this specification and the following drawings in which:

FIGURE 1 is a plan view of an application for sharpening a formed trimming knife used to trim linings in shoe uppers, having three sharpening stations.

FIGURE 2 is a sectional view taken substantially on the line 2-2 of FIGURE 1.

FIGURE 3 is a partial front elevation of a trimming knife being sharpened.

FIGURE 4 is a partial right side elevation showing details of the knife holder.

FIGURE 5 is a perspective view of the trimming knife.

FIGURE 6 is a partial side elevation showing the total slicing or wafering of a cylindrical bar.

FIGURE 7 is a perspective of the wafer.

FIGURE 8 is a partial side elevation showing a dicing operation of the wafer.

FIGURE 9 is a perspective of the diced wafer.

FIGURE 10 is a partial plan view of work being processed against side of wheel.

FIGURE 11 is a partial front sectional view of the rocker arm bracket.

The apparatus shown for a trimming knife sharpening application comprises a machine base 10 incorporating a trough 11 which is used to retain an abrasive mixture 12. Abrasives commonly used are aluminum oxide, silicon carbide, boron carbide and diamond, although silicon carbide has proven satisfactory for most applications except in the processing of diamond where a diamond abrasive mixture must be used. Grit size of the abrasive will vary depending on the degree of finish required. Common sizes range from to 1,000. The abrasive chosen is then mixed in an industrial grade of mineral oil. The concentration of abrasive to mineral oil has a marked effect on the rate of cutting. High concentrations above three pounds of abrasive per gallon of oil are used.

The lower portion of a horizontally rotating carrier wheel 13 having a 60 degree included angle is immersed in the abrasive mixture. The carrier wheel 13 constantly agitates the mixture while a coating of the abrasive mixture covers the wheel to be carried up to the work area. Surface speeds in the vicinity of 400 feet per minute of the carrier wheel are used to prevent the abrasive mixture from being thrown off the wheel. The wheel is fastened to a rotating shaft 14 by a setscrew 49 located in the hub of the carrier wheel. The shaft 14 is supported by sealed bearings 15 located on the inside edges of the trough 11. The shaft 14 further extends into the belt guard 50 where driven pulley 16 is mounted on the end. A V-belt 17 connects the driven pulley 16 to the driving pulley 18 which is attached to the driving means or motor 19. The location of the motor under the machine base prevents the possibility of abrasive splashing and damaging critical motor parts. The knife 20 to be sharpened is allowed to come into contact with the abrasive particles on the wheel while being held in the knife holder 21 with screws 22. The form produced in the knife, in this case an angular one, will be the mate of the form in carrier wheel. During the sharpening of the knife some material is also removed from the carrier wheel. The actual amount removed will be dependent on the materialcomposition of the wheel and the ratio of work area to wheel surface area. The higher the hardness of the carrier wheel, the less the Wear. Fine grain cast iron has proven to be successful for this application.

The knife holder 21 is angularly adjusted on its stud 23 and locked with setscrew 24 in the knife holder bracket 25 to produce a variation in the cutting angle of the knife. The setscrews 26 in knife holder bracket 25 allow angular 'as shown in FIGURE 11.

and longitudinal adjustments of the knife in relation to the rocker arm 27 for additional refinements in the knife cutting angle. A weight 28 adjustable on the rocker arm 27 through setscrew 29 provides means for controlling the rate of cutting by varying the pressure of the knife on the wheel. The greater the pressure, the faster the rate of cutting.

The rocker arm bracket 30 which holds the rocker arm 27, rocks about support rod 31 to bring the knife in and out of contact with the abrasive on the carrier wheel. The rocker arm bracket 30 has two setscrews 32 to prevent it from moving axially along the support rod 31, The setscrews 32 are of the self locking type with a nylon insert and have a cone point that mates into a V-groove in the support rod 31. The setscrews 32 are adjusted so that the rocker arm bracket 30 will be just free to rock about the support rod 31 but without any axial movement. In this manner, the knife will not loose its axial position in relation to the carrier wheel when it is re-sharpened. The support rod 31 is fastened to VS 33 incorporated in the machine base 10 with screws 34. A backstop rod 35 is fastened to VS 36 incorporated in machine base 10 with screws 37 to provide a stop for the rocker arm when it is in the raised position away from the wheel for the purpose of installing and removing knives.

An interval timer 38 is provided so that the machine will shut off automatically after a knife has been sharpened a prescribed amount of time. The amount of time is set each time a knife is to be sharpened and it depends on the degree of dullness in the knife itself. In this manner, the machine may be left unattended freeing an operator to do other work. A well 39 is incorporated in the belt guard 50 so that the knives may be cleaned by dipping in a solvent such as Sovasol manufactured by the Socony- Mobil Company, that is retained in the well. A drain plug 40 is installed in the lower portion of the sidewall of the trough so that the abrasive mixture may be easily drained off after it has lost its ability to cut either through dullness of the abrasive grain or sufficient contamination from particles removed from the knife and carrier wheel. A film control 41 fastened with screw 42 is provided to keep a thin film of abrasive on the surface of the wheel. Periodically it is necessary to adjust the film control inward due to wheel wear.

The slicing or wafering of a cylindrical bar 51 commonly used in the semi-conductor industry is shown in FIGURE 6. The machine base, trough, rocker arm, and power transmission details are the same as the previous application shown in FIGURES 1 and 2. Thin wheels or discs 43 are used as the abrasive carrier wheels. Spacer collars 44 between each disc govern the thickness of each slice. The length of the discs and collars ganged on the rotating shaft is to be equal to or greater than the length of the bar to be sliced. In this manner, the bar is completely sliced in one operation. The thickness of the discs 43 usually is kept to a minimum, approximately .004 to .005 thick, in order to reduce the waste produced during slicing. The cylindrical bar 51 is held to the work holder 45 by a cement 46. The work holder is then fastened to the rocker arm 47 and the operation is performed in the same manner as the knife sharpening application described in FIGURES 1 and 2.

FIGURE 8 shows a wafer 48 during one stage of a dicing operation. The complete dicing operation consists of two cuts taken as shown in FIGURE 9, by indexing the wafer degrees after the first cut. Again the width of the spacing collars 44 between the carrier discs 43 determine the width of each piece.

FIGURE 10 shows work 52 being processed against the side of the wheel 53. The machine base, trough, and power transmission details are the same as shown in FIG- URES 1 and 2. The work 52 is attached to arm 54 which pivots about vertical shaft 55 attached to the machine base. The pressure of the work against the wheel is varied by spring 56, one end being attached to the arm 54 while the other end is attached to adjusting screw 57 which is threaded into projection 58, integral with the machine base.

I claim:

1. A lapping machine comprising a base, a trough mounted on said base, an abrasive mixture in said trough, a solid wheel having a peripheral and side surfaces mounted on a rotary shaft, means for supporting and rotating said shaft, the lower portion of said solid wheel being immersed and rotating in the abrasive mixture, whereby a film of abrasive mixture covers the peripheral and side surfaces of said so lid wheel, means for controlling the thickness of said film of abrasive mixture, means for supporting material to be processed in contact with said film of abrasive mixture.

2. Apparatus as described in claim 1, said means for supporting material to be processed in contact with said film of abrasive mixture consists of an arm rockable about a horizontal axis, means to attach material to said arm, means to vary pressure of material on said arm against said film of abrasive mixture on the peripheral surface of said solid wheel.

3. Apparatus as described in claim 1, said means for supporting material to be processed in contact with said film of abrasive mixture consists of an arm rockable about a vertical axis, means to attach material to said arm, means to vary pressure of material on said arm against said film of abrasive mixture on a side surface of said solid wheel.

References Cited by the Examiner UNITED STATES PATENTS 1,23 0,696 6/ 1917 Filotico. 2,361,961 11/1944 Pruitt 51-98 2,700,255 1/1955 Meier 51263 X LESTER M. SWINGLE, Primary Examiner. 

1. A LAPPING MACHINE COMPRISING A BASE, A TROUGH MOUNTED ON SAID BASE, AN ABRASIVE MIXTURE IN SAID TROUGH, A SOLID WHEEL HAVING A PERIPHERAL AND SIDE SURFACES MOUNTED ON A ROTARY SHAFT, MEANS FOR SUPPORTING AND ROTATING SAID SHAFT, THE LOWER PORTION OF SAID SOLID WHEEL BEING IMMERSED AND ROTATING IN THE ABRASIVE MIXTURE, WHEREBY A FILM OF ABRASIVE MIXTURE COVERS THE PERIPHERAL AND SIDE SURFACES OF SAID SOILD WHEEL, MEANS FOR CONTROLLING THE THICKNESS OF SAID FILM OF ABRASIVE MIXTURE, MEANS FOR SUPPORTING MATERIAL TO BE PROCESSED IN CONTACT WITH SAID FILM OF ABRASIVE MIXTURE. 